Solid state conversion of polycrystalline material

ABSTRACT

Systems, devices, and techniques for manufacturing a crystalline material (e.g., large crystal material) through the solid state conversion of a polycrystalline material are described. A device may be configured to concurrently heat a volume of ribbon, such as an alumina ribbon, using multiple heat sources. For example, a first heat source may heat a first volume of the ribbon and a second heat source may concurrently heat a second volume, for example, within the first volume, where the ribbon may comprise polycrystalline material. The concurrent heating may drive grain growth in the polycrystalline material in at least the second volume, which may convert the polycrystalline material to crystalline material having one or more grains that are larger than one or more grains of the polycrystalline material. The processed ribbon may include a large crystal material or a single crystal material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 17/221,913filed on Apr. 5, 2021, which claims the benefit of priority under 35U.S.C. § 119 of U.S. Provisional Application No. 63/006,967, filed Apr.8, 2020, the content of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The following relates generally to crystalline materials, and morespecifically to converting a polycrystalline material to a crystallinematerial, such as a single crystal material or a large crystal material.

BACKGROUND

Crystalline materials having large grains (e.g., as compared to thegrains of polycrystalline materials) may have physical, optical, andchemical properties that provide benefits across a range of industriesand products. For example, single crystal materials, such as sapphire(e.g., single crystal alpha-alumina), may have high thermalconductivity, a wide transmission wavelength range, increased electricalinsulation, and high strength and wear resistance, particularly at hightemperatures. Accordingly, sapphire and other similar materials may behighly useful in various products and applications, such as optics(e.g., laser crystals, waveguides), electrical components (e.g.,semiconductor devices, substrates for electronics), and ceramics (e.g.,scratch-resistant electronics covers, wristwatch crystals), amongothers.

SUMMARY

The methods, devices, and materials of this disclosure each have severalnew and innovative aspects. This summary provides some examples of thesenew and innovative aspects, but the disclosure may include new andinnovative aspects not included in this summary.

A method for manufacturing is described. The method may include heating,using a first heat source, a first volume of a ribbon, the ribbonincluding a polycrystalline material, and concurrently heating, using asecond heat source while the ribbon is moving relative to at least thesecond heat source and using the first heat source, a second volume ofthe ribbon that is within the first volume, where heating using thefirst heat source and the second heat source may convert at least aportion of the polycrystalline material of the ribbon within the secondvolume to a crystalline material including one or more grains that arelarger than a plurality of grains of the polycrystalline material.

An apparatus may include a processor, memory in electronic communicationwith the processor, and instructions stored in the memory. Theinstructions may be executable by the processor to cause the apparatusto heat, using a first heat source, a first volume of a ribbon, theribbon including a polycrystalline material, and concurrently heat,using a second heat source while the ribbon is moving relative to atleast the second heat source and using the first heat source, a secondvolume of the ribbon that is within the first volume, where heatingusing the first heat source and the second heat source may convert atleast a portion of the polycrystalline material of the ribbon within thesecond volume to a crystalline material including one or more grainsthat are larger than a plurality of grains of the polycrystallinematerial.

Another apparatus may include means for heating, using a first heatsource, a first volume of a ribbon, the ribbon including apolycrystalline material, and means for concurrently heating, using asecond heat source while the ribbon is moving relative to at least thesecond heat source and using the first heat source, a second volume ofthe ribbon that is within the first volume, where heating using thefirst heat source and the second heat source converts at least a portionof the polycrystalline material of the ribbon within the second volumeto a crystalline material including one or more grains that are largerthan a plurality of grains of the polycrystalline material.

In some examples of the method and apparatuses described herein,concurrently heating the second volume using the second heat source mayinclude heating at least a first surface of the ribbon using the firstheat source, where heating at least the first surface of the ribbonheats the first volume of the ribbon, and concurrently heating a secondsurface of the ribbon different from the first surface, where thepolycrystalline material may be converted to the crystalline materialfrom the first surface of the ribbon and extending to a first depth ofthe ribbon from the first surface.

In some examples of the method and apparatuses described herein,concurrently heating the second volume using the second heat source mayinclude scanning the second volume of the ribbon with the second heatsource while the first volume and the second volume are heated by thefirst heat source.

Some examples of the method and apparatuses described herein may furtherinclude operations, features, means, or instructions for depositing,before concurrently heating using the first heat source and the secondheat source, one or more seed crystals on the polycrystalline materialof the ribbon, where an orientation of the crystalline material may bebased on a shape of the one or more seed crystals, or an orientation ofthe one or more seed crystals, or both.

Some examples of the method and apparatuses described herein may furtherinclude operations, features, means, or instructions for moving theribbon relative to the second heat source at a rate that is at least 0.2inches per minute.

In some examples of the method and apparatuses described herein, thefirst heat source includes a convection-type heat source, or a firstradiation-type heat source, or a combination thereof, for heating atleast the first volume. In some examples of the method and apparatusesdescribed herein, the second heat source may include a secondradiation-type heat source for irradiating the second volume withphotons, where the first volume may be larger than the second volume.

In some examples of the method and apparatuses described herein, thefirst heat source may include at least one of a flame, or an oven, or afurnace, or a microwave, and the second heat source may include at leastone of a laser or a focused infrared source.

Some examples of the method and apparatuses described herein may furtherinclude operations, features, means, or instructions for heating thefirst volume of the ribbon using a third heat source, the first volumeincluding a first subset of the polycrystalline material and a secondsubset of the crystalline material, and concurrently heating, using afourth heat source while the ribbon is moving relative to at least thefourth heat source and using the third heat source, the second volume ofthe ribbon that may be within the first volume, where heating using thethird heat source and the fourth heat source may convert at least aportion of the first subset of the polycrystalline material of theribbon within the second volume to the crystalline material includingthe one or more grains that are larger than the plurality of grains ofthe polycrystalline material, and where a depth of the crystallinematerial of the ribbon may increase based on concurrently heating usingthe third heat source and the fourth heat source.

In some examples of the method and apparatuses described herein, heatingusing the first heat source and the second heat source may convert atleast the portion of the polycrystalline material of the ribbon withinthe second volume to the crystalline material while the ribbon is in asolid state.

In some examples of the method and apparatuses described herein, thepolycrystalline material of the ribbon may be at least partiallysintered.

A device for manufacturing may include a support component forsupporting a ribbon that includes a polycrystalline material, a movingcomponent for moving the ribbon, a first heat source for heating a firstvolume of the ribbon, and a second heat source for concurrently heatinga second volume of the ribbon that is within the first volumeconcurrently heated by the first heat source, the moving componentconfigured to move the ribbon relative to at least the second heatsource, where the first heat source and the second heat source areconfigured to convert at least a portion of the polycrystalline materialof the ribbon to a crystalline material including one or more grainsthat are larger than a plurality of grains of the polycrystallinematerial based on heating the first volume and the second volume.

In some examples, the first heat source may be positioned to apply heatto at least a first surface of the ribbon and the second heat source maybe positioned to apply heat to a second surface of the ribbon differentthan the first surface, where the polycrystalline material may beconverted to the crystalline material from the first surface of theribbon and extending to a first depth of the ribbon from the firstsurface.

In some examples, the first heat source may be positioned to apply heatto at least a first surface of the ribbon and the second heat source maybe positioned to apply heat to the first surface of the ribbon, wherethe polycrystalline material may be converted to the crystallinematerial from the first surface of the ribbon and extending to a firstdepth of the ribbon from the first surface.

In some examples, the second heat source may include a radiation-typeheat source configured to scan the second volume of the ribbon using araster pattern, or a scanning pattern, or both.

In some examples, the device includes a tension component for applyingtension to the ribbon to modify a shape of the ribbon while concurrentlyheating the first volume and the second volume.

A ribbon may include a first volume extending from a first side of theribbon to a first depth of the ribbon and including a polycrystallinematerial, and a second volume extending from a second side of the ribbonopposite the first side of the ribbon to a second depth of the ribbonand including a crystalline material having a grain size of at least 100micrometers and including one or more grains that are larger than aplurality of grains of the polycrystalline material, where the seconddepth is at least 1 micrometer.

In some examples, the polycrystalline material includes apolycrystalline ceramic material, or polycrystalline metal material, ora semiconductor material, where the crystalline material includes asapphire material or a single crystal material.

In some examples, a lateral dimension of the grain size of thecrystalline material may be at least 1 millimeter and a longitudinaldimension of the grain size is at least 1 millimeter.

In some examples, the second depth of the second volume may extend toabout a thickness of the ribbon, the thickness of the ribbon being up to1000 micrometers.

In some examples, the one or more grains of the crystalline material maybe oriented in a first direction, where a basal plane of the crystallinematerial may be aligned with a plane of the ribbon based on the one ormore grains of the crystalline material being oriented in the firstdirection.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a device that supports the solid stateconversion of polycrystalline material in accordance with examples asdisclosed herein.

FIG. 2 illustrates an example of a manufacturing scheme that supportsthe solid state conversion of polycrystalline material in accordancewith examples as disclosed herein.

FIGS. 3A and 3B illustrate examples of a ribbon related to the solidstate conversion of polycrystalline material in accordance with examplesas disclosed herein.

FIGS. 4A and 4B illustrate cross sections of a ribbon related to thesolid state conversion of polycrystalline material in accordance withexamples as disclosed herein.

FIG. 5 illustrates an example of a cross section of a ribbon related tothe solid state conversion of polycrystalline material in accordancewith examples as disclosed herein.

FIG. 6 shows a flowchart illustrating a method that supports the solidstate conversion of polycrystalline material in accordance with examplesas disclosed herein.

DETAILED DESCRIPTION

Relatively large crystal materials, such as sapphire (e.g., singlecrystal alpha-alumina), have attracted industrial and research interestdue to their unique properties and applications. For instance, becausesapphire may not have as many grain boundaries, it may have superiorproperties compared to other materials (e.g., as compared topolycrystalline alumina (PCA), which has the same chemistry andcrystalline phase). Other processes used for fabricating ormanufacturing sapphire may include immersing a seed crystal in a meltand continuously pulling the material to form a crystal. However, thisand other processes for manufacturing relatively large crystalmaterials, such as sapphire, are expensive and slow.

In particular, some manufacturing techniques may require extended timeperiods, pre-treatment processes, or both, to obtain relatively largecrystal materials. As one example, techniques for manufacturing sapphirein a solid state (e.g., for high-pressure sodium (HPS) lamp or HPS lightapplications) may include heating PCA at high temperatures (e.g., above1800° C.) under H₂.containing atmosphere. By evaporating self-containedmagnesium oxide (MgO) or by adding other dopants, abnormal grain growth(AGG) may occur and grain boundaries having some mobilities may benucleated and migrated, resulting in sapphire crystals. Such processesmay allow manufacturing sapphire by converting pre-formed PCA, but thesemanufacturing processes may take multiple hours (e.g., more than 10hours) to complete. Further, because the high heat may be applied to alarge area of the PCA, multiple instances of AGG may occur. As a result,sapphire formed by these processes often consists of several largegrains with small (e.g., 15-50 micrometers (μm)) unconverted grainstrapped within the large grains.

In other examples, a heat source may be used for the solid stateconversion of PCA (e.g., PCA tubes) to sapphire. Such techniques,however, may require pre-treatment of the PCA to reduce MgO contentbefore processing (e.g., the PCA tube may require less than 100 partsper million by weight (ppmw) of MgO, and in some cases less than 50ppmwof MgO, prior to processing). These pre-processing techniques used toreduce the MgO content (e.g., prior to the use of the localized heatsource to manufacture the sapphire) increase manufacturing costs andlikewise take an extended amount of time. For instance, the PCA tubeconversion may require 10 hours of heat source processing to avoidthermal shock. In addition, these and other techniques for PCAconversion into sapphire may not be capable of controlling the locationor direction of the conversion (e.g., controlling the thickness of theconverted sapphire). Accordingly, improved techniques to reduce the timeand cost for manufacturing sapphire and other crystalline materialshaving large grains may be desirable.

The new techniques and devices described herein may provide forefficient manufacturing of relatively large crystal materials, such assingle crystal materials, from a ribbon or sheet of polycrystallinematerial (e.g., PCA). In particular, aspects of the present disclosuremay include processing the ribbon or sheet to convert polycrystallinematerial into one or more grains of a large crystal material or a singlecrystal material (such as sapphire), which may be completed relativelyquickly and with reduced manufacturing costs.

The described techniques may include concurrently heating the ribbon orsheet of polycrystalline material using multiple heat sources, where atleast a portion of the ribbon or sheet may be in a general area heatedby a first heat source (e.g., a flame, a furnace, an oven, a microwave)along with concurrent heating by a second heat source that may be moreconcentrated, localized, or focused (e.g., a laser, focused infrared(IR)) in a limited area within the general area. In some cases, thelocalized heat source may be scanned across the ribbon while the ribbonis heated by the first heat source. There may be relative motion betweenthe ribbon and one or more of the heat sources (e.g., where the ribbonmay move through a volume heated by the first heat source while aparticular area of the ribbon is scanned by the localized heat source)in some examples. In any case, the concurrent heating by two or moredifferent heat sources may initiate and drive grain growth and produceat least large grains on at least one surface of the processedribbon/sheet.

In some examples, the described techniques may use a sintered (or atleast partially sintered) solid state polycrystalline ribbon or sheet,or a solid state ribbon or sheet rolled from thicker material. Theribbon or sheet may have relatively smaller thickness (e.g., 40 μm) ascompared to PCA tubes or other materials, and the ribbon or sheet mayalso not have restrictions on length or width. Further, the ribbon maybe flexible and may allow for various manufacturing techniques, such asa roll-to-roll process. Further, there may not be any composition orcontent restrictions on the ribbon or sheet (such as the MgO content ofthe ribbon) prior to processing using the described techniques. Forinstance, a ribbon of polycrystalline material may include 500 ppmw ofMgO, and the ribbon may not require pre-processing (e.g., heat treatmentor other processes) to reduce the MgO content. Accordingly, thedescribed techniques may advantageously reduce processing time and costfor manufacturing the large crystal material.

The described techniques may also convert the polycrystalline materialof the ribbon or sheet at increased speeds, where the polycrystallinematerial may be converted at speeds of 0.2 inches per minute or more(e.g., 2 inches per minutes, 20 inches per minute, and so forth),thereby enabling the processing of a ribbon or sheet of polycrystallinematerial in significantly less time than other techniques (e.g., on theorder of seconds and minutes instead of many hours). In some aspects,the conversion of the polycrystalline material into larger crystalmaterial, such as sapphire, may generally be controlled such that thelarger crystal material is manufactured from the surface of the ribbonor sheet (e.g., to a particular depth). In other cases, the conversionof the polycrystalline material into crystalline material having largegrains (e.g., sapphire) may be achieved through the full thickness ofthe ribbon/sheet. The large grains of the processed material may beoriented in a first direction such that a basal plane (planeperpendicular to principal axis in crystal system) of the processedmaterial may be aligned with a surface of the ribbon. In addition, theprocess may be a roll-to-roll process or a roll-to-sheet (e.g.,singulated sheet) process.

After processing using the described techniques, the ribbon comprisingthe crystalline material having relatively large grains may be used in avariety of applications, including transparent scratch resistant phonecovers, planar waveguides, laser crystals, creep resistant ceramics,creep resistant metals, substrates for electronics, substrates forsuperconductors, high temperature ceramic superconductors, ionconductors, and so forth. It is noted that, although some examples ofthe present disclosure are described with reference to convertingalumina ceramics to large crystal materials (e.g., converting PCA tosapphire), the present disclosure is not limited to these materials. Forexample, the processing of the ribbon or sheet may not be limited tocrystalline ceramics, but may also be used in crystalline metals,semiconductor materials, or other materials.

Features of the disclosure are initially described in the context of adevice for manufacturing as described with reference to FIG. 1 .Features of the disclosure are further described in the context ofprocessing techniques, processed ribbons including crystallinematerials, cross-sectional views of alumina ribbons, and flowcharts, asdescribed with reference to FIGS. 2-6 .

FIG. 1 illustrates an example of a device 100 that supports the solidstate conversion of polycrystalline material in accordance with examplesas disclosed herein. The device 100 may include a first heat source 105and a second heat source 110, which may be used to apply heat to aribbon 115 that includes a polycrystalline material 120 (e.g., PCA). Thedevice 100 may be configured for processing the ribbon 115 to convertthe polycrystalline material 120 of the ribbon 115 to a crystallinematerial 125 (e.g., a relatively larger grain crystal material, a singlecrystal material, a monocrystalline material, a sapphire material, orthe like) having one or more grains that are larger than grains of thepolycrystalline material 120. In some examples, the device may include amoving component 155, or a tension component 160, or a support component165, or any combination thereof.

Processing the ribbon 115 by the device 100 may include applying energy(e.g., separately, concurrently, simultaneously) from multiple heatsources (e.g., the first heat source 105 and the second heat source 110)to the ribbon 115.

In some examples, the first heat source 105 may be an example of a heatsource that facilitates heat transfer via convection or via radiation(e.g., a convection-type heat source, a radiation-type heat source), orboth. For instance, the first heat source 105 may be an example of anoven, a flame, a torch, or a burner that applies heat to the ribbon 115,where the first heat source 105 may heat a first volume 130 of theribbon 115. The first heat source 105 may also heat a volume 140 that islarger than the first volume 130 (e.g., including the atmospheresurrounding the ribbon 115), where the volume 140 may encompass (e.g.,include) at least the first volume 130 of the ribbon 115. As an example,the first heat source 105 may be an example of a furnace, a microwave,an oven, or the like, that heats the first volume 130 of the ribbon 115.Accordingly, the first heat source 105 may heat the ribbon 115 through athickness of the ribbon 115.

The first heat source 105 of the device 100 may be positioned at one ormore various locations, orientations, or proximities relative to theribbon 115. For instance, the first heat source 105 may be positionedopposite a first surface 150-a of the ribbon 115, such as when the firstheat source 105 includes a flame or a burner. A distance between thefirst heat source 105 and the ribbon 115 may also be controlled orconfigured such that a temperature at which the first volume 130 isheated may be controlled, or modified, or both for processing the ribbon115. Different orientations and placements of the first heat source 105are possible. The first heat source 105 may be configured to control atemperature of at least the first volume 130 of the ribbon 115 (e.g., inresponse to, or to be able to compensate for, a configuration of thesecond heat source 110). Further, the first heat source 105 may includea filament or other component of a device that generates heat.

The second heat source 110 may be an example of a localized orconcentrated heat source that heats a second volume 135 of the ribbon115, for example, that may be within the first volume 130 of the ribbon115. Because the first volume 130 may be heated by the first heat source105, the second volume 135, which may be within the first volume 130,may be concurrently heated by the first heat source 105 and the secondheat source 110. The concurrent application of heat from both the firstheat source 105 and the second heat source 110 at the second volume 135may drive gain growth within the second volume 135 and convert thepolycrystalline material 120 to the crystalline material 125 havingrelatively large grains (e.g., a single crystal material).

The second heat source 110 may be an example of a radiation-type heatsource, such as a laser, or focused IR, or the like. The second heatsource 110 may be configured to apply heat to a concentrated area orlocation on a surface 150 of the ribbon 115 (e.g., and extending to adepth of the ribbon 115 to heat a volume of the ribbon 115) using one ormore patterns or schemes. Additionally, the second heat source 110 maybe configured to control a temperature of the ribbon 115 in the secondvolume 135 (e.g., based on accounting for or adjusting for aconfiguration of the first heat source 105). The second heat source 110may be positioned at one or more various locations, orientations, andproximities relative to the ribbon 115. For instance, as illustrated bysecond heat source 110-a, the second heat source 110-a may be positionedopposite a second surface 150-b of the ribbon 115. Alternatively, thesecond heat source 110 may be positioned opposite the first surface150-a of the ribbon 115, as illustrated by second heat source 110-b. Thesecond heat source 110 (e.g., second heat source 110-a, second heatsource 110-b) may apply heat to the ribbon (e.g., to the second volume135 of the ribbon 115) from one or more various angles and directionsrelative to either the first surface 150-a or the second surface 150-b.In any case, the second heat source 110 may heat the second volume 135of the ribbon 115 by irradiating the second volume 135. It is noted thatother types of heat sources, and additional heat sources, are possibleand contemplated, and the examples described herein are not to beconsidered limiting.

Heating the second volume 135 of the ribbon 115 may include scanning thesecond heat source 110 across the ribbon 115, where the scanning may bein accordance with a particular pattern. As an example, the second heatsource 110 may be an example of a laser, and the laser may be scannedacross the ribbon 115 using a raster pattern. Additionally oralternatively, the laser may form a wide beam (such as a light sheet orother configuration) which may continuously heat different portions ofthe second volume 135 as the wide beam is scanned across the ribbon 115.In some examples, the wide beam may be scanned across the ribbon 115while the second volume 135 is concurrently heated by the first heatsource 105. Thus, the second heat source 110 and the ribbon 115 may bemoved relative to each other.

The described techniques for converting the material of the ribbon 115may be transient, continuous, or stationary. For instance, the ribbonmay be moved or translated in some direction by the moving component 155of the device 100, where the moving component 155 may be configured tomove the ribbon 115 (e.g., continuously, according to some movementconfiguration, or the like). Additionally or alternatively, the ribbon115 may be stationary, and the device 100 and/or the heat sources may becontinuously moved relative to the ribbon 115. In other examples, boththe ribbon 115 and the device 100 may be moving with respect to eachother. Further, the ribbon 115 may be moved by the moving component 155relative to either the first heat source 105, the second heat source110, or both. The moving component 155 may be an example of a motoralone or with one or more other components or other device capable ofmoving one or both of the ribbon 115 or the device 100, or thecomponents thereof.

Moving the ribbon 115 relative to the device 100 (or one or more of theheat sources) while the second volume 135 of the ribbon 115 isconcurrently heated by the heat sources may enable grain growth alongthe length of the ribbon 115, which may result in manufacturing aluminaribbons with relatively large grains fully covering at least one surface(e.g., fully covering a width of the ribbon).

In particular, the first volume 130 and the second volume 135 maydynamically change based on the motion of the ribbon 115. In someexamples, the first volume 130 and the second volume 135 may advancealong the length of the ribbon 115 as the ribbon 115 is moving (e.g.,while the first heat source 105 is applied to the ribbon and while thesecond heat source 110 is applied to the ribbon 115). As such, theportion(s) of the ribbon concurrently heated by the first heat source105 and by the second heat source 110 may result in the polycrystallinematerial 120 on at least the first surface 150-a (and to some relateddepth/volume of the ribbon) to be converted to the crystalline material125 along the length of the ribbon 115.

Put another way, a portion of the ribbon 115 within the second volume135 may be heated by the first heat source 105 and the second heatsource 110, driving grain growth at that portion. As the ribbon 115moves, the portion of the ribbon 115 that is subjected to both the firstheat source 105 and the second heat source 110 may dynamically increasein the direction of the length of the ribbon 115 (e.g., a longitudinaldirection of the ribbon), which may convert additional polycrystallinematerial 120 to the crystalline material 125 while the ribbon 115 moves.Additionally, and as described in further detail below, the crystallinematerial 125 may be manufactured in a lateral direction of the ribbon115. In one example, the crystalline material 125 may, for example,increase in size outward from a center of the ribbon 115 towards theedges of the ribbon 115 as the ribbon is concurrently heated by thefirst heat source 105 and the second heat source 110.

The conversion of the polycrystalline material 120 to the crystallinematerial 125 having grains that are larger than grains of thepolycrystalline material 120 may generally occur from a surface 150 ofthe ribbon 115 through a depth of the ribbon 115. For instance, and asdescribed in further detail with reference to FIGS. 3B, 4A, and 4B, thepolycrystalline material 120 may be converted in a volume of the ribbon115 that extends from the first surface 150-a to a first depth. In somecases, the conversion to the crystalline material 125 may occur on asame surface 150 to which the first heat source 105 is applied (e.g.,the first surface 150-a of the ribbon 115), such as in the case wherethe first heat source 105 is a flame, torch, or burner. In otherexamples, conversion to the crystalline material 125 on a surface 150 amay be irrespective of the location, position, or orientation of one orboth of the first heat source 105 or the second heat source 110. As aresult, the processed ribbon 115 may include both a portion or volume ofpolycrystalline material 120 (e.g., through a depth of the ribbon 115from the second surface 150-b) and another portion or volume ofcrystalline material 125 having relatively large grains (e.g., through adepth of the ribbon 115 from the first surface 150-a).

As an illustrative example of the conversion process performed by thedevice 100, among others, a laser or other concentrated, localized heatsource may be used in addition to a another heating source to convert apolycrystalline alumina ribbon to produce an alumina ribbon withrelatively large grains covering one surface 150. A propane torch flame(e.g., the first heat source 105) may be used to heat alumina ribbonsfrom one side (e.g., corresponding to the first surface 150-a) and acarbon dioxide (CO2) laser (e.g., the second heat source 110) may beused to scan across the alumina ribbon at generally the same area orlocation from the other side (e.g., corresponding to the surface 150-b).That is, the alumina ribbon alumina ribbon may travel though an areaheated by the propane torch flame with the CO2 laser scanning thealumina ribbon. The temperature of the alumina ribbon may be controlledby both the first heat source 105 (e.g., the flame) and the second heatsource 110 (the CO2 laser).

In this example, the starting materials of the ribbon 115 (e.g., priorto processing using device 100) may include a fully sintered (or atleast partially sintered) alumina ribbon (e.g., comprising Al₂O₃). Insome cases, the alumina ribbon may have 99.95 percent purity and auniform polycrystalline microstructure. In some cases, the aluminaribbon may have greater than 99 percent relative density and thepolycrystalline material 120 of the ribbon 115 may have a 1.5 μm grainsize. In some example, the alumina ribbon may be 500 ppm MgO by weight.The alumina ribbon may be processed with this or a different content ofMgO by weight, and the alumina ribbon may not require pre-treatment toreduce or modify the MgO content. The ribbon 115 may also excludedopants, such as silicon dioxide (SiO₂), for example, on the surface ofthe ribbon 115.

The ribbon 115 may be an example of an alumina ribbon ceramic, aflexible ceramic ribbon, or the like. For example, the ribbon 115 of thepresent example may be an alumina ribbon 40 μm thick, and may be 1 inchwide, and 4 inches long. However, other ribbon dimensions areconsidered. For example, the alumina ribbon may be wider than lcm,(e.g., 2.5 cm wide, or may be wider than 10 cm, or wider than 30 cm).Likewise, the alumina ribbon may be longer than lcm (e.g., 5 cm, 10 cm,but may be as long as an area may allow). Further, while the aluminaribbon may be 40 μm thick, it may be any thickness (e.g., between 20 and1000μm). It is also noted that although aspects of the presentdisclosure are described with reference to the ribbon 115, a sheet(e.g., an alumina sheet) or other similar structure may be used.

The laser beam (e.g., of the second heat source 110) may, for example,have a diameter of 8 mm and a power of 88 watts (W). However, a laserhaving different power and diameter may be used. In one example, thelaser may be rastered across the alumina ribbon at a speed of 4500 mm/swith a scanning width of 60 mm. In another example, the laser may becontinuously scanned across the width of the ribbon at a speed of 4500mm/s (e.g., instead of rastering). At the end of scan, the laser beammay be stepped by 0.025 mm. In some examples, the effective lasermovement speed along the length of the alumina ribbon may be 1.8 mm/s,but different speed may be possible. In some cases, the laser may scan aribbon length of 1.5 inch in less than 30 seconds. The speed of theprocess performed by device 100 for converting the polycrystallinematerial 120 to the crystalline material 125 may be 0.2 inches perminute, or more. For instance, the ribbon may be moved at a speed of 2inches per minute, 20 inches per minute, or 200 inches per minute. Assuch, the alumina ribbon may be processed with enhanced speed, ascompared to other processes that take multiple hours.

When the alumina ribbon passes through the propane flame torch and theCO2 laser (e.g., the second volume 135 being concurrent heated by thefirst heat source 105 and the second heat source 110), large grainsfully covering the first surface 150-a of the alumina ribbon may beachieved. Thus, the processed ribbon 115 may include at least a portionof crystalline material 125 that includes one or more grains (e.g.,large grains) that are larger than grains of the polycrystallinematerial 120. The concurrent application of the heat sources may resultin converting the polycrystalline material 120 to single crystalmaterial (e.g., sapphire). In some cases, a lateral size of the largegrains may be larger than 500 μm. In some examples, the lateral size ofthe large grains may be as large as the lateral size of the ribbon. Insome examples, the size of the large grains in depth may be larger than10 μm and may be as deep as the thickness of the ribbon. As such, theprocessed ribbon may be a single crystal sapphire ribbon throughout.

In some examples, tension may be used (e.g., during or after) theprocess to convert polycrystalline alumina ribbons to alumina ribbonswith relatively large grains fully covering one surface 150, where thetension may modify or change the shape of the converted alumina ribbons.Here, the tension component 160 may apply tension to one or morelocations of the ribbon 115. As an illustrative example, tension may becontrolled by applying a weight on one end of the ribbon 115 while theother end is being pulled by the moving component 155 (e.g., a motor) ata steady speed when the alumina ribbon passes through the first heatsource 105 (e.g., a propane flame torch) and the second heat source 110(e.g., a laser). In one example, the tension component 160 may apply aweight of 200 grams to the ribbon 115 while the ribbon 115 may be pulledby the moving component 155 at a speed of 2 inches per minute. Thetension component 160 may apply tension to the ribbon 115 at the sametime the ribbon 115 (e.g., the second volume 135) is beingsimultaneously heated by the first heat source 105 and the second heatsource 110. In other examples, the tension component 160 may applytension after the ribbon 115 is simultaneously heated by the first heatsource 105 and the second heat source 110.

In some examples, the ribbon 115 may be processed multiple times, whichmay increase the amount of crystalline material (e.g., single crystalmaterial) of the processed ribbon 115. For instance, after the ribbon115 is processed by device 100, resulting in a ribbon having therelatively large crystal material (e.g., crystalline material 125) alongthe length of the ribbon 115, one or more heat sources, such as thefirst heat source 105 or the second heat source 110 or both, may be usedfor applying heat to the ribbon 115, for example, a second time. In suchcases, the additional processing of the ribbon 115 may result in agreater amount of crystalline material 125 having large grains beingformed along the length of the ribbon 115 (e.g., an increased depth ofsapphire material from the first surface 150-a).

More specifically, additional processing by applying the first heatsource 105 or the second heat source 110 (e.g., to the second volume135) or both, may result in some portion or subset of polycrystallinematerial 120 (e.g., that remains after initial processing of the ribbon115) to be converted to the crystalline material 125. As described withreference to FIGS. 4A and 4B, a depth of the crystalline material 125may increase as a result of additional processing the ribbon multipletimes (e.g., sequentially). The ribbon 115 may be processed any numberof times, which in some cases may result in manufacturing a ribbon 115of the crystalline material 125 (e.g., containing no or trace amounts ofthe polycrystalline material 120). In some examples, the second volume135 of the ribbon 115 may be concurrently heated by the first heatsource 105 or the second heat source 110 or both multiple times (e.g.,additional scans by the second heat source 110). Additionally oralternatively, the second volume 135 of the ribbon 115 may beconcurrently heated by a third heat source (e.g., similar to the firstheat source 105) and a fourth heat source (e.g., similar to the secondheat source 110). In some cases, the first heat source 105, the secondheat source 110, the third heat source, and the fourth heat source maybe the same or different types of heat sources. Additionally oralternatively, the ribbon 115 may be processed in a different directionor orientation from an initial processing. For instance, the ribbon 115may be processed once, then flipped over and processed again.

The support component 165 of the device 100 may hold the ribbon 115, forexample, prior to processing. The support component 165 may be anexample of a spool or similar device that holds the ribbon 115 prior toprocessing and potentially provides some rigidity for processing.Additionally or alternatively, the processing of the ribbon 115 may be aroll-to-roll process, and a second support component may be used to holdthe ribbon 115 after the ribbon 115 is processed. In other cases, theprocessed ribbon 115 may be singulated into two or more portions ofcrystalline material 125 having large grains.

One or more aspects performed by device 100 may result in aluminaribbons 115 with large grains fully covering at least one surface 150.The processed ribbons 115 may have a shape or form factor that allowsfor various applications and uses, and the alumina ribbons produced bydevice 100 may be rolled. The described manufacturing techniques and thedevice 100 may provide for increased speed and reduced manufacturingcosts, among other benefits. For example, alumina ribbons (or sheets ofalumina or PCA) converted to relatively large grain crystal materials,such as sapphire, may improve many properties of the alumina, such asscratch resistance, thermal conductivity, optical transmittance, etc. Inaddition, the conversion of the alumina ribbons may be performed whilethe ribbon is in a solid state (e.g., without melting of the ribbon115).

The described manufacturing techniques may result in long single crystalribbons or sheets of various compositions. The described techniques mayalso make large size, thin alumina ribbons with large grains fullycovering at least one surface. Such a form factor, together with thesuperior properties of large crystal materials and single crystalmaterials described herein, is unique in the thin ceramic substrateindustry. As such, the processed ribbon 115 described herein may provideone or more advantages in a variety of commercial applications, such assubstrates for electronics, covers for electronics (e.g., phones,watches), insulators, etc. Further, the described techniques may lowermanufacturing costs and also may not require high temperature furnacesand/or controlled atmosphere. The process may be continuous with a speedof at least 0.2 inches per minute, and the potential roll-to-rollprocess may further lower manufacturing costs. In some cases, thedescribed process and apparatus may make thin, single crystal ribbonsand/or sheets with increased length (e.g., multiple meters in length).

FIG. 2 illustrates an example of a manufacturing scheme 200 thatsupports the solid state conversion of polycrystalline material inaccordance with examples as disclosed herein. The manufacturing scheme200 may be implemented by a device, such as the device 100 describedwith reference to FIG. 1 . For example, the manufacturing scheme mayinclude a ribbon 215 (e.g., an alumina ribbon) that comprisespolycrystalline material 220, which may be an example of the ribbon 115described with reference to FIG. 1 .

The manufacturing scheme 200 may be used to process the ribbon using afirst heat source (e.g., a flame, a torch, a furnace, an oven) that mayheat a first volume 230 of the ribbon 215 and using a second heat sourcethat concurrently heats a second volume 235 of the ribbon 215 within thefirst volume 230. The concurrent heating of at least the second volume235 of the ribbon 215 may convert the polycrystalline material 220 tocrystalline material 225 that has one or more grains that are largerthan the grains of the polycrystalline material 220. In some examples,the crystalline material 225 may be a single crystal material. In somecases, the crystalline material 225 may be a sapphire material.

The manufacturing scheme 200 may include the use of a nucleation crystal250 (e.g., a seed crystal) deposited on the ribbon 215, where one ormore different orientations of the crystalline material 225 may beobtained by utilizing the nucleation crystal 250. Through the use of themanufacturing scheme 200, an alumina ribbon with large grains coveringat least one surface of the ribbon 215 may be manufactured.

As described herein, the application of multiple heat sources to theribbon 215 may drive grain growth of a relatively large crystal material(e.g., the crystalline material 225) on a surface of the ribbon 215 to adepth of the ribbon 215.

The relatively large crystal material may have a particular orientationon the ribbon 215. For example, one or more grains of the relativelylarge crystal material may have an orientation such that a basal planeof the large crystal material is aligned or nearly aligned with a planeor surface of the ribbon 215. In some cases, a nucleation crystal 250may be used to initiate grain growth for the ribbon 215. For instance,the nucleation crystal 250 may be deposited on the ribbon 215 and whenthe volume of the ribbon 215 including the nucleation crystal 250 iswithin the second volume 235 (e.g., being concurrently heated bymultiple heat sources), the nucleation crystal 250 may initiate graingrowth of the crystalline material 225 having large grains. In otherembodiments the crystals may be otherwise aligned and/or the system maynot include a basal plane.

Further, as illustrated by manufacturing scheme 200, the growth of thecrystalline material 225 may be initiated from or near a location of thenucleation crystal 250. The grain growth may then spread to the edges ofthe ribbon 215 as the ribbon 215 moves in relation to the heat sources(alternatively, as the heat sources move in relation to the ribbon).Specifically, the crystalline material 225 may increase in size in alateral dimension of the ribbon 215 as well as a longitudinal direction(corresponding to a length of the ribbon 215) as successive portions ofthe ribbon 215 are dynamically located within the second volume 235being concurrently heated. In some examples, the crystalline material225 having large grains may cover a surface of the ribbon 215 and mayhave a width that is the same as a width 255 of the ribbon 215.

Some compositions and orientations of the crystalline material 225 maybe controlled or enhanced via the use of the nucleation crystal 250(e.g., through forced nucleation by the seed crystal), and differentcrystalline shapes or structures may be used for the nucleation crystal250. As an illustrative example, the nucleation crystal 250 may have ahexagonal crystal orientation. In other examples, an alternate hexagonalorientation 260 may be used for the nucleation crystal 250. Additionallyor alternatively, a cubic crystal orientation 265 may be used for thenucleation crystal 250. In some cases, an alternate cubic orientation270 may be used for the nucleation crystal 250. Other shapes, sizes, andorientations of the nucleation crystal 250 may be used, and the examplesdescribed should not be considered to be limiting. The shape,orientation, or structure of the nucleation crystal 250 may modify theorientation of the formed crystalline material 225 on the surface and inthe volume of the ribbon 215.

FIGS. 3A and 3B illustrate examples of a ribbon 300 that relates tosolid state conversion of polycrystalline materials.

For example, FIG. 3A may illustrate a surface of a ribbon 300 that hasbeen processed using the techniques described herein. More specifically,the ribbon 300 may illustrate an example of an alumina ribbon, such as aribbon 115 or a ribbon 215 described with reference to FIGS. 1 and 2 ,processed by concurrently heating the ribbon 300 using a first heatsource (e.g., a flame, an oven) and a second heat source (e.g., alaser). In some examples, the ribbon 300 may comprise other materials,such as crystalline metals, semiconductor materials, or other ceramicmaterials.

The surface of the ribbon 300 may accordingly include a relatively largecrystal material as a result of the concurrent heating. In particular,the ribbon 300 may include a relatively large crystal material or singlecrystal material on its surface. A processed area 305 of the ribbon 300that at least the second heat source (e.g., a laser, focused IR, orother radiation-type heat source) was applied may have a highertranslucency than an un-processed area 310 of the ribbon 300. Theprocessed area 305 (e.g., a lasered area) may accordingly include one ormore large grains 315 that have formed on the surface of the ribbon 300.Further, within the processed area 305, there may be a region 320 witheven higher translucency. In some examples, the size of the region 320may be similar to the size of the region where the ribbon 300 was heatedby the first heat source, such as in the example where a flame or atorch was used as the first heat source, as described herein.

FIG. 3B may illustrate an example of a cross section 301 of the ribbon300. For example, the cross section 301 of the processed ribbon 300 mayillustrate one or more portions of the region 320 described withreference to FIG. 3A. As described herein, the large grains 315 may beon a surface 325 of the ribbon 300. The large grains 315 may correspondto a volume of the ribbon 300 beginning at the surface 325 of the ribbon300 and extending to a depth of the ribbon 300. For example, the depthof the large grains 315 from the surface 325 may be at least 10 μm. Insome examples, the large grains 315 may have a dimension that is atleast hundreds of microns long (e.g., laterally along the surface 325 ofthe ribbon 300), and may also extend longitudinally (e.g., correspondingto a length of the ribbon 300) for hundreds of microns. However, thevolume of the large grains 315 may have different dimensions in one ormore directions.

The cross section 301 also illustrates a polycrystalline material 330 ofthe ribbon 300 having multiple grains 335, where the one or more largegrains 315 (e.g., of a crystalline material) may be larger than thegrains 335 of the polycrystalline material 330. The grains 335 may be ofvarying size and may have a different orientation (e.g., a randomorientation) with respect to each other. By contrast, a large grain 315may have a same orientation as another large grain 315, or may have anorientation that corresponds to a hexagonal or triclinic crystalstructure. In some examples, a large grain 315 may be an example of asingle crystal material. The single crystal material may not have agrain boundary (e.g., other than the surface 325) and may extend acrossthe width of the ribbon. Further, in some examples, the single crystalmaterial may have an atomic structure that repeats periodically acrossthe volume of the large grain 315.

In some examples, concurrent heating using multiple heat sources (e.g.,laser processing and the additional flame heating) of the ribbon 300 mayresult in different microstructures when processed under differentconditions. For instance, an original microstructure of the ribbon 300may have some porosity after sintering. In the microstructureillustrated by cross section 301 (e.g., after having heat appliedsimultaneously by two different heat sources), a large crystal (e.g.,the large grains 315) may be formed. In some aspects, the grains 335 ofthe polycrystalline material 330 be larger than an original size ofpolycrystalline grains in volume of the un-processed ribbon (e.g.,corresponding to the un-processed area 310).

In some cases, by applying the same laser processing on the aluminaribbon 300 without the first heat source (e.g., only applying heat usingthe second heat source), the microstructure of the ribbon 300 may becamedenser without much grain growth.

Alternatively, by applying a high power laser (e.g., as the second heatsource) for processing on the alumina ribbon 300 and without the firstheat source, some grains may grow to a size slightly larger than thegrains 335 of the polycrystalline material 330. Such grain growth may bea result of a higher temperature achieved by way of the increased powerof the laser. In some cases, no large crystals may be present throughlaser processing only, where the addition of the concurrent heat fromthe first heat source (e.g., a flame, an oven, etc.) may result in theformation of the large crystals, even in cases where no change wasobserved by heating using the first heat source only.

In some examples, a large grain 315 may be oriented with a basal plane(0001, or 001) of the crystalline material (e.g., a sapphire crystal)aligned in the plane of the ribbon 300. The opposite side of the ribbon300 may have small grain size polycrystals (e.g., polycrystallinematerial 330; less than 100 μm average grain size on the surface, suchas less than 80 μm, such as less than 50 μm, such as less than 20 μm,such as less than 10 μm, such as on the order of 5 μm or less averagegrain size on the surface of the opposite size of the ribbon 300), whichmay correspond to an unoriented polycrystalline alpha-alumina. Bycontrast, the grain size of the crystalline material may be at least μmon average, as measured on a surface of the ribbon 300, such as at least150 μm average grain size, such as at least 200 μm, at least 500 μm. Insome embodiments, a lateral dimension of the grain size of one or moregrains of the crystalline material may be at least 1 millimeter and alongitudinal dimension of the grain size is at least 1 millimeter.Support of sintered, smaller grain size portion of the ribbon 300 mayhold the ribbon 300 together as the heat sources soften and allowformation of the larger grain size portion of the ribbon 300.

FIGS. 4A and 4B illustrate examples of cross sections 400 and 401 of aprocessed ribbon that relates to the solid state conversion ofpolycrystalline material in accordance with examples as disclosedherein. The cross sections 400 and 401 illustrate an alumina ribbon 405that has been processed one or more times according to the techniquesdescribed herein. The ribbon 405 may be an example of an alumina ribbon(e.g., PCA, alumina ribbon ceramic), such as a ribbon 115, a ribbon 215,or a ribbon 300 described with reference to FIGS. 1, 2, 3A, or 3B, thathas been processed by concurrently heating the ribbon using a first heatsource and a second heat source. In some examples, the ribbon may beprocessed by a manufacturing device, such as device 100, as describedwith reference to FIG. 1 .

In some examples, the alumina ribbon 405 may be scanned by a localizedheat source (e.g., a laser) multiple times while being concurrentlyheated using another heat source (e.g., a furnace, a flame, etc.). Inparticular, FIG. 4A illustrates a cross section of an alumina ribbon 405that has been processed once using the described techniques (e.g., by aCO2 laser with a propane torch flame). At least a portion the ribbon 405may have been heated using a first heat source and a second, differentheat source resulting in large grains fully covering at least onesurface 410 (e.g., surface 410-a) of the ribbon 405.

The processed ribbon 405 may include a first volume 415-a comprisingpolycrystalline material and a second volume 420-a comprisingcrystalline material having one or more grains that are larger thangrains of the polycrystalline material. The first volume 415-a mayextend from a surface 410-b to a first depth of the ribbon 405.Similarly, the second volume 420-a may extend from the surface 410-a toa second depth of the ribbon 405. Based on the processing of the ribbon405 using the concurrent heat sources, the depth of the second volume420-a (e.g., comprising large crystal material) may be at least 1 μm.However, as illustrated, second volume 420-a may be at least 10 μm deep.In other cases, the depth of the second volume 420-a (e.g., after beingprocessed once) may be the same as or about the same as a thickness ofthe ribbon 405 (where the depth of the first volume 415-a ofpolycrystalline material may be zero or near zero).

The ribbon 405 may be processed one or more additional times, and FIG.4B illustrates an example of an alumina ribbon (e.g., ribbon 405) thathas been scanned, for example, four times (e.g., by a CO2 laser whileconcurrently heated with a propane torch flame). As a result of theadditional heat processing, the thickness of the large grains includedin the second volume 420-a of the ribbon 405 may increase in size.Specifically, after being processed one or more additional times, atleast first subset of polycrystalline material from the first volume415-a may be converted into large crystal material (e.g., crystallinematerial). Accordingly, the crystalline material of the second volume420-a may increase in size (e.g., depth).

As a result of the additional processing, and as illustrated by thecross section 401, the first volume 415-b may be less than the firstvolume 415-a and the second volume 420-b may be greater than the secondvolume 420-a. Here, the depth of the second volume 420-b may be greaterthan the depth of the second volume 420-a, where the depth of the secondvolume 420-b may, for example, be between 15 μm and 20 μm. In somecases, the depth of the second volume 420-b (e.g., after one or moreadditional processing operations) may be the same as or nearly the sameas the thickness of the ribbon 405 (where the depth of the first volume415-b of polycrystalline material may be zero or near zero). Theincrease in the depth of the second volume 420-b including the largecrystal material may follow a transitional parabolic law of graingrowth.

FIG. 5 illustrates an example of cross section of a ribbon 500 thatrelates to the solid state conversion of polycrystalline material inaccordance with examples as disclosed herein. The cross section of theribbon may be an example of an alumina ribbon (e.g., PCA, alumina ribbonceramic), such as a ribbon 115, a ribbon 215, a ribbon 300, or a ribbon405 described with reference to FIGS. 1, 2, 3A, 3B, 4A, or 4B that hasbeen processed by concurrent heating using a first heat source and asecond heat source.

The cross section of the ribbon 500 may illustrate a large crystal 505which has been formed after processing using the described techniques.Additionally, the cross section of the ribbon 500 illustrates a surface510 of the large crystal 505 and an edge 515 (e.g., a corner) of thelarge crystal 505. The surface 510 may correspond to a flat surface ofthe alumina ribbon 500. As shown on the surface 510, multiple roundedhexagonal terraces 520 (e.g., hexagonal terraces 520-a and 520-b) of thelarge crystal 505 may be present. These hexagonal terraces 520-a and520-b illustrate that a basal plane orientation of the large crystal 505may be aligned with a plane of the alumina ribbon 500. In addition, thesurface 510 of the large crystal 505 may illustrate multiple partiallyrounded hexagons.

Here, the ledges and terraces of the large crystal 505 may providesurface diffusion that minimizes a surface energy. The hexagonalterraces 520 (as well as the partial rounded hexagons) may reflect anunderlying crystal structure of the large crystal 505(hexagonal/triclinic) and show that a basal plane may be nearly in theplane of the alumina ribbon 500. Such an orientation may beadvantageous, for example, if the structure is to be used for opticalpurposes where light is transmitted normal to the plane of the ribbon(e.g., for phone or tablet touch screens). As described herein, otherorientations of the large crystal 505 may be achieved through thedescribed techniques.

FIG. 6 shows a flowchart illustrating a method 600 that supports solidstate conversion of polycrystalline material in accordance with examplesas disclosed herein. The operations of method 600 may be implemented bya manufacturing system or one or more controllers associated with amanufacturing system. In some example, the operations of method 600 maybe implemented by a device, such as a device 100 described withreference to FIG. 1 , among other examples. In some examples, one ormore controllers may execute a set of instructions to control one ormore functional elements of the manufacturing system or device toperform the described functions. Additionally or alternatively, one ormore controllers may perform aspects of the described functions usingspecial-purpose hardware.

At 605, the method 600 may include heating, using a first heat source, afirst volume of a ribbon, the ribbon including a polycrystallinematerial. The operations of 605 may be performed according to themethods described herein. The operations of 605 may be performed by adevice, such as a device 100 or 200 described with reference to FIGS. 1and 2 .

At 610, the method 600 may include concurrently heating, using a secondheat source while the ribbon is moving relative to at least the secondheat source and using the first heat source, a second volume of theribbon that is within the first volume, where heating using the firstheat source and the second heat source converts at least a portion ofthe polycrystalline material of the ribbon within the second volume to acrystalline material including one or more grains that are larger than aplurality of grains of the polycrystalline material. The operations of610 may be performed according to the methods described herein.

In some examples, an apparatus as described herein may perform a methodor methods for manufacturing, such as the method 600. The apparatus mayinclude features, means, or instructions (e.g., a non-transitorycomputer-readable medium storing instructions executable by a processor)for heating, using a first heat source, a first volume of a ribbon, theribbon including a polycrystalline material. The apparatus may includefeatures, means, or instructions for concurrently heating, using asecond heat source while the ribbon is moving relative to at least thesecond heat source and using the first heat source, a second volume ofthe ribbon that is within the first volume, where heating using thefirst heat source and the second heat source converts at least a portionof the polycrystalline material of the ribbon within the second volumeto a crystalline material including one or more grains that are largerthan a plurality of grains of the polycrystalline material.

In some examples of the method 600 and the apparatus described herein,the operations, features, means, or instructions for concurrentlyheating the second volume using the second heat source may furtherinclude operations, features, means, or instructions for heating atleast a first surface of the ribbon using the first heat source, whereheating at least the first surface of the ribbon heats the first volumeof the ribbon, and concurrently heating a second surface of the ribbondifferent from the first surface, where the polycrystalline material maybe converted to the crystalline material from the first surface of theribbon and extending to a first depth of the ribbon from the firstsurface. In some examples of the method 600 and the apparatus describedherein, the operations, features, means, or instructions forconcurrently heating the second volume using the second heat source mayfurther include operations, features, means, or instructions forscanning the second volume of the ribbon with the second heat sourcewhile the first volume and the second volume are heated by the firstheat source.

Some examples of the method 600 and the apparatus described herein mayfurther include operations, features, means, or instructions fordepositing, before concurrently heating using the first heat source andthe second heat source, one or more seed crystals on the polycrystallinematerial of the ribbon, where an orientation of the crystalline materialis based on a shape of the one or more seed crystals, or an orientationof the one or more seed crystals, or both. Some examples of the method600 and the apparatus described herein may further include operations,features, means, or instructions for moving the ribbon relative to thesecond heat source at a rate that is at least 0.2 inches per minute.

In some examples of the method 600 and the apparatus described herein,the first heat source includes a convection-type heat source, or a firstradiation-type heat source, or a combination thereof, for heating atleast the first volume. In some examples of the method 600 and theapparatus described herein, the second heat source includes a secondradiation-type heat source for irradiating the second volume withphotons, the first volume being larger than the second volume. In someexamples of the method 600 and the apparatus described herein, the firstheat source includes at least one of a flame, or an oven, ora furnace,or a microwave. In some examples of the method 600 and the apparatusdescribed herein, the second heat source includes at least one of alaser or a focused IR source.

Some examples of the method 600 and the apparatus described herein mayfurther include operations, features, means, or instructions for heatingthe first volume of the ribbon using a third heat source, the firstvolume including a first subset of the polycrystalline material and asecond subset of the crystalline material. Some examples of the method600 and the apparatus described herein may further include operations,features, means, or instructions for concurrently heating, using afourth heat source while the ribbon is moving relative to at least thefourth heat source and using the third heat source, the second volume ofthe ribbon that is within the first volume, where heating using thethird heat source and the fourth heat source converts at least a portionof the first subset of the polycrystalline material of the ribbon withinthe second volume to the crystalline material including the one or moregrains that are larger than the plurality of grains of thepolycrystalline material, and where a depth of the crystalline materialof the ribbon increases based on concurrently heating using the thirdheat source and the fourth heat source.

In some examples of the method 600 and the apparatus described herein,heating using the first heat source and the second heat source convertsat least the portion of the polycrystalline material of the ribbonwithin the second volume to the crystalline material while the ribbon isin a solid state. In some examples of the method 600 and the apparatusdescribed herein, the polycrystalline material of the ribbon is at leastpartially sintered.

It should be noted that the methods described herein describe possibleimplementations, and that the operations and the steps may be rearrangedor otherwise modified and that other implementations are possible.Further, portions from two or more of the methods may be combined.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

The terms “electronic communication,” “conductive contact,” “connected,”and “coupled” may refer to a relationship between components thatsupports the flow of signals between the components. Components areconsidered in electronic communication with (or in conductive contactwith or connected with or coupled with) one another if there is anyconductive path between the components that can, at any time, supportthe flow of signals between the components. At any given time, theconductive path between components that are in electronic communicationwith each other (or in conductive contact with or connected with orcoupled with) may be an open circuit or a closed circuit based on theoperation of the device that includes the connected components. Theconductive path between connected components may be a direct conductivepath between the components or the conductive path between connectedcomponents may be an indirect conductive path that may includeintermediate components, such as switches, transistors, or othercomponents. In some examples, the flow of signals between the connectedcomponents may be interrupted for a time, for example, using one or moreintermediate components such as switches or transistors.

The description set forth herein, in connection with the appendeddrawings, describes example configurations and does not represent allthe examples that may be implemented or that are within the scope of theclaims. The term “exemplary” used herein means “serving as an example,instance, or illustration,” and not “preferred” or “advantageous overother examples.” The detailed description includes specific details toproviding an understanding of the described techniques. Thesetechniques, however, may be practiced without these specific details. Insome instances, well-known structures and devices are shown in blockdiagram form to avoid obscuring the concepts of the described examples.

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

The various illustrative blocks, components, and modules described inconnection with the disclosure herein may be implemented or performedwith a general-purpose processor. A general-purpose processor may be amicroprocessor, but in the alternative, the processor may be anyprocessor, controller, microcontroller, or state machine. A processormay also be implemented as a combination of computing devices.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described herein can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of at least one of A, B, or C meansA or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, asused herein, the phrase “based on” shall not be construed as a referenceto a closed set of conditions. For example, an exemplary step that isdescribed as “based on condition A” may be based on both a condition Aand a condition B without departing from the scope of the presentdisclosure. In other words, as used herein, the phrase “based on” shallbe construed in the same manner as the phrase “based at least in parton.”

The description herein is provided to enable a person having ordinaryskill in the art to make or use the disclosure. Various modifications tothe disclosure will be apparent to those skilled in the art, and thegeneric principles defined herein may be applied to other variationswithout departing from the scope of the disclosure. Thus, the disclosureis not limited to the examples and designs described herein, but is tobe accorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method of manufacturing, comprising: heating,using a first heat source, a first volume of a ribbon, the ribboncomprising a polycrystalline material; and concurrently heating, using asecond heat source while the ribbon is moving relative to at least thesecond heat source and using the first heat source, a second volume ofthe ribbon that is within the first volume, wherein heating using thefirst heat source and the second heat source converts at least a portionof the polycrystalline material of the ribbon within the second volumeto a crystalline material comprising one or more grains that are largerthan a plurality of grains of the polycrystalline material.
 2. Themethod of claim 1, wherein concurrently heating the second volume usingthe second heat source comprises: heating at least a first surface ofthe ribbon using the first heat source, wherein heating at least thefirst surface of the ribbon heats the first volume of the ribbon; andconcurrently heating a second surface of the ribbon different from thefirst surface, wherein the polycrystalline material is converted to thecrystalline material from the first surface of the ribbon and extendingto a first depth of the ribbon from the first surface.
 3. The method ofclaim 1, wherein concurrently heating the second volume using the secondheat source comprises: scanning the second volume of the ribbon with thesecond heat source while the first volume and the second volume areheated by the first heat source.
 4. The method of claim 1, furthercomprising: depositing, before concurrently heating using the first heatsource and the second heat source, one or more seed crystals on thepolycrystalline material of the ribbon, wherein an orientation of thecrystalline material is based at least in part on a shape of the one ormore seed crystals, or an orientation of the one or more seed crystals,or both.
 5. The method of claim 1, further comprising: moving the ribbonrelative to the second heat source at a rate that is at least 0.2 inchesper minute.
 6. The method of claim 1, wherein the first heat sourcecomprises a convection-type heat source, or a first radiation-type heatsource, or a combination thereof, for heating at least the first volume,and wherein the second heat source comprises a second radiation-typeheat source for irradiating the second volume with photons, the firstvolume being larger than the second volume.
 7. The method of claim 1,wherein the first heat source comprises at least one of a flame, or anoven, or a furnace, or a microwave, and wherein the second heat sourcecomprises at least one of a laser or a focused infrared source.
 8. Themethod of claim 1, further comprising: heating the first volume of theribbon using a third heat source, the first volume comprising a firstsubset of the polycrystalline material and a second subset of thecrystalline material; and concurrently heating, using a fourth heatsource while the ribbon is moving relative to at least the fourth heatsource and using the third heat source, the second volume of the ribbonthat is within the first volume, wherein heating using the third heatsource and the fourth heat source converts at least a portion of thefirst subset of the polycrystalline material of the ribbon within thesecond volume to the crystalline material comprising the one or moregrains that are larger than the plurality of grains of thepolycrystalline material, and wherein a depth of the crystallinematerial of the ribbon increases based at least in part on concurrentlyheating using the third heat source and the fourth heat source.
 9. Themethod of claim 1, wherein heating using the first heat source and thesecond heat source converts at least the portion of the polycrystallinematerial of the ribbon within the second volume to the crystallinematerial while the ribbon is in a solid state.
 10. The method of claim1, wherein the polycrystalline material of the ribbon is at leastpartially sintered.